The use of catheters to access the vascular system and other anatomical spaces has become a standard procedure in modern medicine. Catheters may be used for infusion of therapeutics, hyperalimentation, and other substances. Catheters can be used for the insertion or placement of substances or apparatuses for treating various disorders. Catheters can also be used to permit or enhance perfusion in humans and animals. Catheters may be used for specific purposes, such as irradiation or dilation. Similarly, catheters may be modified, e.g., by the addition of balloon systems, for specific purposes such as dilation.
Catheters used for many purposes may be inserted in relatively straight and/or relatively large vascular spaces or other anatomical spaces. Other catheters, however, must be inserted into relatively small and tortuous vascular spaces or tracts. In order to achieve proper placement of such catheters, the catheters must be manipulated or guided through the vascular system or other anatomical spaces.
The current invention is applicable to various catheters designed for multiple purposes for uses where the catheter must be manipulated or guided in order to serve its therapeutic purpose. Although the current invention applies to catheters designed for multiple purposes, the problem to be solved will be described in detail for catheters used to treat disorders of the vascular system and, in particular, disorders of the coronary artery system.
The first percutaneous arterial angioplasty took place in 1963 when a physician accidently advanced an angiographic catheter through an occluded iliac artery, reestablishing flow. Subsequently, the physician began deliberately dilating peripheral arterial stenoses using a series of tapered catheters inserted percutaneously over a guidewire.
During the past 30 years, the procedure, which has become known as percutaneous transluminal angioplasty (PTA), has become an established procedure in the management of a variety of obstructive disorders of the vascular system. PTA has been applied to obstructive lesions of the iliac, femoral, renal, coronary and cerebral vascular systems. Theoretically, any vessel of sufficient size to allow atraumatic passage of a balloon catheter is suitable for PTA.
One use of PTA that exemplifies the problem solved by the current invention is the application of the procedure to disorders of the coronary circulation. PTA applied to coronary arteries is referred to as percutaneous transluminal coronary angioplasty (PTCA).
PTCA involves the inflation of a distensible balloon within a coronary stenosis and subsequent dilation of the narrowing. After baseline coronary angiography, a large-lumen guiding catheter is advanced to the appropriate coronary ostium. A small flexible guide wire is advanced through the guiding catheter into the coronary artery and across the stenosis. A balloon catheter is then advanced over the wire and positioned across the stenosis. The balloon is usually inflated with 6 to 12 atm of pressure for 30 to 120 seconds and then deflated.
During use of some catheters, the biological path in which treatment is occurring is occluded by the catheter. This occlusion is not desirable. A catheter that avoids interruption of the circulation through the treated segment is desirable. Another problem with current catheters is that they do not provide the doctor with the ability to control dosage of radiation by properly positioning the irradiation source from the area to be treated. The dosage of the ionizing radiation for causing a particular biological affect depends upon (1) the capability of the primary radiation source to emit the radiation, (2) the time of exposure, and (3) the distance from the source to the irradiation target. A catheter which maintains an uniform distance from the ionizing source introduced in the catheter to the tissue to be radiated, thereby allowing for proper radiation of the tissue is desirable. These and other problems in current catheter are addressed by the catheter of the present invention.
Low profile guiding catheters are expensive. They require expensive plastics, special manufacturing processes and cost generally in the $100 to $250 range per catheter. Furthermore, since the catheters are disposable this cost is per patient. Although other equipment used like the radiation source, guide wire, and automatic machine radiation source placing machine are very expensive, these components are reusable and are amortized over many years and many patients. Most catheters are specialized and can only be used for a specific medical procedure. They are not versatile or multi-purpose. Thus, in order to reduce costs, it would be desirable to have one catheter that would allow a doctor to perform a variety of procedures.
For many patients the percutaneous coronary angioplastics with balloon (“PTCA”) or angioplastic procedure is not successful. PTCA without a stent or net has approximately a 50% first-time success rate. PTCA with a stent or net as approximately an 80% first-time success rate. Improvements in the catheters and in the procedure are necessary to prevent re-treatment and save money.
The major applications of the catheter are treatment of stenotic coronary veins and arteries as well as peripheral arteries (carotids, renal iliacs, femoral, popliteans). Each of these veins and arteries to be recanalized by any of the existing endovascular techniques (balloon angioplasty, atherectomy, laser evaporation) including cases when biological or metallic endovascular protesic devices are used, all of them causing a different degree of biological reaction of the vessel wall, that can result in new significant reduction of the vessel lumen (restenosis). A catheter that limits reduction of vessel lumen is desirable.
Ionizing radiation has been used in diagnostic, therapeutic, and other medical procedures over the years. Ionizing radiation treatment is used for both benign and malignant diseases. In systems where radiation is delivered through pathways, wire systems including a radioactive source are currently being tested for transporting the radioactive source to the treatment area. Manufacturers of wire systems in the US include: Neocardia, US Surgical Corporation, Best Industries, and Novoste. Manufacturers of wire systems in Europe include: Nucletron and Schnneider.
What is needed are better catheters.
What is needed are better catheter components.
What is needed are better systems for catheter manipulation and support.
What is needed are better and/or safer systems and methods for delivering ionizing radiation.
What is needed are better and/or safer wire systems and methods for ionizing radiation treatment.